It is known to provide conduit for non-metallic pipes and wiring with fire-activated collars that crush the pipe when activated by heat. Such collars are generally mounted onto the conduit at the exterior end of a penetration or passage through a wall or floor. Patents that have issued that are in this category include:
______________________________________ United States 4,916,800 United States 4,848,043 United States 4,894,966 United States 5,103,609 United States 4,788,800 United States 4,109,423 United States 4,850,385 United States 4,307,546 United States 5,129,202 ______________________________________
Generally, such devices also incorporate flanges that extend outwardly from the collar to seal-off the boundary of a wall or floor penetration into which the conduit passes. Such flanges are particularly appropriate when the penetration is larger than the conduit in diameter. They are also useful for cast-in-place conduits as a means for supporting the collar in place adjacent to the wall or floor through which the conduit passes.
Another class of device provides for conduit-collapsing means that is fitted around a conduit located within the interior of the wall or floor penetration.
Prior patents in this class include:
______________________________________ United States 4,796,401 United States 4,364,210 United States 4,105,592 United States 4,493,173 United States 4,888,925 ______________________________________
The environment in which such devices are intended to operate requires that they have a long lifetime. Once installed at a wall or floor penetration, the expectation is that these firestop devices will last the life of the building. This could be for 25 or more years.
When installed in floor penetrations, such firestop devices are exposed to water on occasions. This can occur during the course of construction and/or in the event of mechanical failure of the piping system within a building. Even units installed on the under, ceiling-side of a floor penetration can have water drip-through from the floor above. Both wall and floor units are exposed to moisture in the air as the majority are installed within ceiling plenums.
While it has been known that some intumescent materials, such as hydrated sodium silicate and mono-ammonium phosphate are hygroscopic and need to be properly protected to prevent deterioration through the absorption of atmospheric moisture, sufficient precautions to protect intumescent materials from extended, long-time exposure to moisture have not been adequately addressed. Other intumescent materials contain water, and may benefit from provisions to prevent them from drying-out excessively.
Another feature of some existing firestop systems is that the intumescent closure device will be installed by fitting it onto the standard conduit otherwise employed at the work site as an add-on element. Such conduit is contemporaneously made of polypropylene, poly-ethylene, PVC or ABS plastic, sometimes reinforced with glass fibres. Plastics of this type are heat-softenable or "fusible", and therefore are particularly suited to being crushed by the expansion of intumescent material in the presence of heat.
It is preferable, for security of operation, to ensure that the intumescent closure components and conduit to be collapsed are matched. This cannot always be assured when the conduit is supplied on-site, separately from the firestop closure mechanism which is attached separately as an add-on element.
It is with these background considerations in mind, along with other objectives, such as ease of installation, that the invention herein has been conceived.
The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest and more specific forms will then be further described, and defined, in each of the individual claims which conclude this Specification.